It has been possible to re-purpose such additional refresh cycles as an additional Rowhammer attack vector, see https://www.usenix.org/conference/usenixsecurity22/presentat...
That's not a particularly big assist, and doesn't sound hard to mitigate.
If TRR pushed the rows it refreshes 10% closer to triggering their own TRR, then those 300,000 accesses would have triggered multiple refreshes in the target row.